Perfluoroalkyl substituted compounds are widely used in a large number of applications where the unique ability of perfluoroalkyl groups to lower the surface energy of solids, or organic or aqueous solutions, is of decisive importance. In polymers, the presence of perfluoroalkyl groups reduces the polymer surface-free energy to below 15 dynes/cm, and such polymers are used by the textile industry to make fabrics not only water repellent, but also oil repellent.
R.sub.f -surfactants which are otherwise like their hydrocarbon analogues in that they are either anionic, cationic, nonionic or amphoteric, but which contain perfluoroalkyl groups reduce the surface tension of aqueous or organic liquids to extremely low levels, down to 15 dynes/cm, as compared to 25-30 dynes/cm obtainable with conventional surfactants. Such low surface tensions allow these liquids, which may be molten polymers or polymer solutions or emulsions, to wet substrates which are otherwise impossible to wet. Therefore properties which depend on good wetting are often substantially improved, such as adhesion and surface smoothness, and such coating deficiencies as crawling, "fisheyes," "orange peel," etc. are largely eliminated. Numerous R.sub.f -surfactants have been described in U.S. Pat. Nos. 2,915,554; 3,274,244; 3,621,059; 3,668,233; and German Offenlegungsschrift No. 2,215,388.
R.sub.f -surfactants of the prior art cited above are used for coating systems to help in wetting and to prevent crawling and other side effects of poor coatings. These R.sub.f -surfactants are nonionic in nature because ionic compounds are poorly compatible with resins. All the R.sub.f -surfactants described are non-reactive.